From: Roland Scheidegger <srol...@vmware.com>
Similar to const buffers. The driver must not emit any tes-related
state if tes
is disabled, since the hw slots are all shared by VS, therefore it would
overwrite them (the mesa state tracker might not do this, but it would be
perfectly legal to do so).
Nevertheless I think the dirty state tracking logic in the driver is
fundamentally flawed when tes is disabled/enabled, since it looks to
me like
the VS (and TES) state would not get reemitted to the correct slots
(if it's
not dirty anyway). Unless I'm missing something...
Theoretically, the overwrite problem could be solved by using
non-overlapping
resource slots for TES and VS (since we're not even close to using
half the
resource slots), but it wouldn't work for constant buffers nor
samplers, and
for VS would still need to propagate changes to both LS and VS, so
probably
not a useful idea.
Unfortunately there's zero coverage of this with piglit, since all
tessellation
shader tests are just shader_runner tests, which are unsuitable for
testing
any kind of state dependency tracking issues (so I can't even quickly
hack
something up to proove it and fix it...).
TCS otoh is just fine - like GS it has its own hw slots.
---
src/gallium/drivers/r600/evergreen_state.c | 4 ++++
src/gallium/drivers/r600/r600_state_common.c | 15 +++++++++++++++
2 files changed, 19 insertions(+)
diff --git a/src/gallium/drivers/r600/evergreen_state.c
b/src/gallium/drivers/r600/evergreen_state.c
index 4cc48dfa11..fb1de9cbf4 100644
--- a/src/gallium/drivers/r600/evergreen_state.c
+++ b/src/gallium/drivers/r600/evergreen_state.c
@@ -2334,6 +2334,8 @@ static void
evergreen_emit_tcs_sampler_views(struct r600_context *rctx, struct r
static void evergreen_emit_tes_sampler_views(struct r600_context
*rctx, struct r600_atom *atom)
{
+ if (!rctx->tes_shader)
+ return;
evergreen_emit_sampler_views(rctx,
&rctx->samplers[PIPE_SHADER_TESS_EVAL].views,
EG_FETCH_CONSTANTS_OFFSET_VS +
R600_MAX_CONST_BUFFERS, 0);
}
@@ -2404,6 +2406,8 @@ static void
evergreen_emit_tcs_sampler_states(struct r600_context *rctx, struct
static void evergreen_emit_tes_sampler_states(struct r600_context
*rctx, struct r600_atom *atom)
{
+ if (!rctx->tes_shader)
+ return;
evergreen_emit_sampler_states(rctx,
&rctx->samplers[PIPE_SHADER_TESS_EVAL], 18,
R_00A414_TD_VS_SAMPLER0_BORDER_INDEX, 0);
}
diff --git a/src/gallium/drivers/r600/r600_state_common.c
b/src/gallium/drivers/r600/r600_state_common.c
index 4364350487..a434156c16 100644
--- a/src/gallium/drivers/r600/r600_state_common.c
+++ b/src/gallium/drivers/r600/r600_state_common.c
@@ -1723,6 +1723,21 @@ static bool r600_update_derived_state(struct
r600_context *rctx)
UPDATE_SHADER_CLIP(R600_HW_STAGE_VS, vs);
}
}
+
+ /*
+ * XXX: I believe there's some fatal flaw in the dirty state
logic when
+ * enabling/disabling tes.
+ * VS/ES share all buffer/resource/sampler slots. If TES is enabled,
+ * it will therefore overwrite the VS slots. If it now gets
disabled,
+ * the VS needs to rebind all buffer/resource/sampler slots - not
only
+ * has TES overwritten the corresponding slots, but when the VS was
+ * operating as LS the things with correpsonding dirty bits got
bound
+ * to LS slots and won't reflect what is dirty as VS stage even
if the
+ * TES didn't overwrite it. The story for re-enabled TES is similar.
+ * In any case, we're not allowed to submit any TES state when
+ * TES is disabled (the state tracker may not do this but this looks
+ * like an optimization to me, not something which can be relied
on).
+ */
/* Update clip misc state. */
if (clip_so_current) {
